Dual image formation on separate supports of photocurable composition

ABSTRACT

This invention is directed to forming two silverless continuous tone photographic images from a sandwich comprising two UV transparent outer support layers and a pigment or dye filled photosensitive composition as the inner layer by exposing said composition to actinic radiation e.g., UV light through imagebearing transparencies adjacent each outer support layer to selectively insolublize the UV exposed areas of said composition, peeling said outer support layer apart and removing soluble portions of the composition in the unexposed areas thereby forming a silverless, continuous tone, photographic image on each outer support layer.

nited States Patent [451 Mar. 21, 1972 [54] DUAL IMAGE FORMATION ONSEPARATE SUPPORTS OF PHOTOCURABLE COMPOSITION [72] Inventor: Robert J.Bailey, College Park, Md. [73] Assignee: W. R. Grace & Co I [22] Filed:June 16, 1969 [21] App]. No.: 833,723

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3,427,l6l 2/1969 Laridon-etal. ..96/36.3 3,353,955 11/1967 Colgrove..58/28 Primary Examiner-Norman G. Torchin Assistant Examiner-Edward C.Kimlin Attorney-Richard P. Plunkett and Kenneth E. Prince [57] ABSTRACTThis invention is directed to forming two silverless continuous 'tonephotographic images from a sandwich comprising two UV transparent outersupport layers and a pigment or dye filled photosensitive composition asthe inner layer by exposing said composition to actinic radiation e.g.,UV light through image-bearing transparencies adjacent each outersupport layer to selectively insolublize the UV exposed areas of saidcomposition, peeling said outer support layer apart and removing solubleportions of the composition in the unexposed areas thereby forming asilverless, continuous tone, photographic image on each outer supportlayer.

14 Claims, No Drawings DUAL IMAGE FORMATION N SEPARATE SUPPORTS OFPHOTOCURABLE COMPOSITION This invention relates to silverlessphotography.

Continuous tone photographic materials used today consist of silverhalide emulsions coated on supports, the silver halide being convertedto metalic silver by the action of light and a developer. This systemhas several disadvantages. One disadvantage is the skyrocketing cost ofsilver due to silver being in such short supply. Another drawback isthat all work must be done in the dark, thus necessitating costlydarkrooms. Our materials do not employ silver and do not requireexpensive, inconvenient darkrooms as they are sensitive only to UVlight. Also, conventional photographic printing materials are coated onpaper since the support has to be permeable to the aqueous solution ofdeveloper. in our system the image is formed on a transparent supportthat can then be laminated to any kind of backing-cloth, wood, plastic,metal, etc., to give a wide variety of effects.

Recently, Dupont has marketed Crolux," a photopolymerizable compositionthat yields images on exposure to light. Crolux, however, gives onlyblack and white images and no intermediate gray tones and thus is notadaptable to use as a photographic print medium.

One object of this invention is to prepare continuous tone photographicimages and prints which do not contain silver. Another object is toprepare silverless photographic images and prints which can be processedin normal room lighting. Yet another object of the instant invention isto prepare silverless photographic images and prints which do notrequire costly chemicals in their development. A still further object ofthis invention is to prepare two separate photographic images from asingle photosensitive composition. Other objects will become apparentfrom a reading hereinafter.

Similarly the invention comprises sandwiching a pigment or dye filledphotosensitive composition between two UV transparent support layers,exposing said composition to actinic radiation through an image-bearingtransparency adjacent each support layer thereby curing thephotosensitive composition in the exposed areas, peeling said supportlayers apart and removing uncured portions of the composition in theunexposed areas thereof thus forming a silverless, continuous tone,photographic image on each support layer. Said image, if positive, canbe laminated to a background material e.g., a high reflectance materialsuch as white-pigmented polyvinyl chloride to give a continuous tonephotographic print. Depending upon whether the dye or pigment in thephotosensitive composition is black or white, the resulting image willform a photographic print on being laminated to the opposite coloredbackground material.

It is critical in carrying out this invention that the thickness of thephotosensitive composition layer be not less than 2 mils. Photosensitivecomposition layers of less than 2 mils results in the polymer beingcured clear through to the other support layer under normal exposuretimes and conditions which precludes obtaining two images. Thus for thepurposes of this invention the photosensitive composition layer shouldhave a uniform thickness ranging from 2 to 50 mils, preferably 2 tomils.

As used herein the term photosensitive composition means a compositionhaving a viscosity in the range 0 to 20 million centipoises at 130 Cwhich is solidified either by photocuring or photopolymerization or bothon exposure to actinic light.

Photosensitive compositions which are operable in the instant inventionare set out in copending applications having U.S. Ser. No. 674,773 filedOct. 12, 1967, U.S. Ser. No. 779,596 filed Nov. 27, 1968, and U.S. Ser.No. 828,724 entitled Silverless Photographic Printing Paper" filed May28, 1969, all assigned to the same assignee and all incorporated byreference herein. In said systems a composition consisting of a 2 to 98parts by weight of a polyene containing at least two unsaturated carbonto carbon bonds per molecule, 98 to 2 parts by weight of a polythiolcontaining two or more thiol groups per molecule, and a photocuring rateaccelerator, i.e., a photosensitizer, e.g., benzophenone, is cured onexposure to UV light.

As used therein polyenes and polyynes refer to a simple or complexspecies of alkenes or alkynes having a multiplicity, i.e., at least tworeactive carbon to carbon unsaturated functional groups per averagemolecule. For example, a diene is a polyene that has two reactive"carbon to carbon double bonds per average molecule, while a diyne is apolyyne that contains in its structure two reactive carbon to carbontriple bonds per average molecule. Combinations of double and triplebonds within the same molecule are also operable. An example of this ismonovinylacetylene, which is a polyeneyne under our definition. Forpurposes of brevity all these classes of compounds will be referred toherein as polyenes.

As used herein the term reactive unsaturated carbon to carbon groupsmeans groups which will react under proper conditions as set forthherein with thiol groups to yield the thioether linkage as contrasted tothe term unreactive carbon to carbon unsaturation which means groupswhen found in aromatic nucleii (cyclic structures exemplified bybenzene, pyridine, anthrocene, tropolone and the like) which do notunder the same conditions react with thiols to give thioether linkages.in the instant invention, products from the reaction of polyenes withpolythiols which contain two or more thiol groups per average moleculeare called polythioether polymers or polythioethers.

One group of polyenes operable in the instant invention to react withpolythiols to form a photographic image is that taught in a copendingapplication having Ser. No. 617,801 filed Feb. 23, 1967, assigned to thesame assignee and incorporated herein by reference. This group includesthose having a molecular weight in the range 50 to 20,000, a viscosityranging from 0 to 20 million centipoises at 70 C. of the general formulawherein X is a member of the group consisting of R and RCEC;

m is at least 2; R is independently selected from the group consistingof hydrogen, halogen, aryl, substituted aryl, cycloalkyl, substitutedcycloalkyl, aralkyl, substituted aralkyl and alkyl and substituted alkylgroups containing one to 16 carbon atoms and A is a polyvalent organicmoiety free of l reactive carbon to carbon unsaturation and (2)unsaturated groups in conjugation with the reactive ene or yne groups inX. Thus A may contain cyclic groupings and minor amounts of hetero atomssuch as N, S, P, or 0 but contains primarily carbon-carbon,carbon-oxygen or silicon-oxygen chain linkages without any reactivecarbon to carbon unsaturation.

Examples of operable polyenes from this group include, but are notlimited to l. crotyl-terminated polyurethanes which contain two reactivedouble bonds per average molecule in a near terminal position of theaverage general formula:

whereinxisatleastl,

2. the following structure which contains terminal reactive" doublebonds:

where x is at least 1, and

4. the following structure which contains near terminal reactive doublebonds: CH;(CHz)1-CH=CH(CH7)7C(OC;He)xO-? A second group of polyenesoperable in the instant invention includes unsaturated polymers in whichthe double or triple bonds occur primarily within the main chain of themolecules. Examples include conventional elastomers (derived primarilyfrom standard diene monomers) such as polyisoprene, polybutadiene,styrene-butadiene rubber, isobutylene-isoprene rubber, polychloroprenestyrene-butadieneacrylonitrile rubber and the like, unsaturatedpolyesters, polymides, and polyurethanes derived from monomerscontaining reactive unsaturation, e.g., adipic acid-butenediol,l,6-hexane-diamine-fumaric acid and 2,4-tolylene diisocyanate-butenediolcondensation polymer and the like.

A third group of polyenes operable in this invention includes thosepolyenes in which the reactive unsaturated carbon to carbon bonds areconjugated with adjacent unsaturated groupings. Examples of operablereactive conjugated ene systems include, but are not limited to, thefollowing:

A few typical examples of polymeric polyenes which contain conjugatedreactive double bond groupings such as those described above arepolyethyleneether glycol diacrylate having a molecular weight of about750, polytetramethyleneether glycol dimethacrylate having a molecularweight of about 1,175, the triacrylate of the reaction product oftrimethylolpropane with moles of ethylene oxide and the like.

Another polyene operable in the present invention to form photographicimages is where n is 2 to 135. This polyene, because it is watersoluble, is easily developed in a water bath after imaging.

Included in the term polyenes as used herein are those materials whichin the presence of an inert solvent, aqueous dispersion or plasticizerfall within the viscosity range set out above at C.

As used herein, the term polythiol refers to the simple or complexorganic compounds having a multiplicity, i.e., at least two, of pendantor terminally positioned SH functional groups per average molecule.

On the average the polythiols must contain two or more SHgroups/molecule. They usually have a viscosity range of 0 to 20 millioncentipoises (cps) at 130 C. as measured by a Brookfield Viscometer.Included in the term polythiols" as used herein are those materialswhich in the presence of an inert solvent, aqueous dispersion orplasticizer fall within the viscosity range set out above at 130 C.Operable polythiols in the instant invention usually have molecularweights in the range 5020,000, preferably l00-l0,000.

The polythiols operable in the instant invention can be exemplified bythe general formula where n is at least 2 and R is a polyvalent organicmoiety free from reactive" carbon to carbon unsaturation. Thus R maycontain cyclic groupings and minor amounts of hereto atoms such as N, S,P or 0 but primarily contains carbon-hydrogen, carbon-oxygen, orsilicon-oxygen containing chain linkages free of any reactive carbon tocarbon unsaturation.

One class of polythiols operable with polyenes in the instant inventionto obtain an essentially odorless cured polythioether photographicmedium are esters of thiol-containing acids of the general formula: HSRCOOH where R is an organic moiety containing no reactive" carbon tocarbon unsaturation with polyhydroxy compounds of the general formula:

R1" OH) it was, W c 7., n where R is an organic moiety containing noreactive carbon to carbon unsaturation and n is 2 or greater. Thesecomponents will react under suitable conditions to give a polythiolhaving the general structure:

where R and R are organic moieties containing no reactive carbon tocarbon unsaturation and n is 2 or greater.

Certain polythiols such as the aliphatic monomeric polythiols (ethanedithiol, hexamethylene dithiol, decamethylene dithiol,tolylene-2,4-dithiol, etc.) and some polymeric polythiols such as athiol-terminated ethylcyclohexyl dimercaptan polymer, etc., and similarpolythiols which are conveniently and ordinarily synthesized on acommercial basis although having obnoxious odors, are operable in thisinvention. Examples of the polythiol compounds preferred for thisinvention because of their relatively low odor level and fast curingrate include, but are not limited to, esters of thioglycolic acid (HSCHCOOH), amercaptopropionic acid (HS CH(CH )COOH) and B-mercaptopropionicacid (HS- CH CH COOH) with polyhydroxy compounds such as glycols,triols, tetraols, pentaols, hexaols, etc. Specific examples of thepreferred polythiols include, but are not limited to, ethylene glycolbis(thioglycolate), ethylene glycol bis (B-mercaptopropionate),trimethylolpropane tris(thioglycolate), trimethylolpropane tris(,B-mercaptopropionate), pentaerythritol tetrakis (thioglycolate) andpentaerythritol tetrakis (B-mercaptopropionate), all of which arecommercially available. A specific example of a preferred polymericpolythiol is polypropyleneether glycol bis (fl-mercaptopropionate) whichis prepared from polypropyleneether glycol (e.g., Pluracol P2010,Wyandotte Chemical Corp.) and B-mercaptopropionic acid byesterification.

The preferred polythiol compounds are characterized by a low level ofmercaptan-like odor initially, and after reaction give essentiallyodorless cured polythioether end products which are commercially usefulresins or elastomers for a photographic medium.

As used herein the term odorless means the substantial absence of thewell known offensive and sometimes obnoxious odors that arecharacteristic of hydrogen sulfide and the derivative family ofcompounds known as mercaptans.

The term functionality" as used herein refers to the average number ofene or thiol groups per molecule in the polyene or polythiol,respectively. For example, a triene is a polyene with an average ofthree reactive carbon to carbon unsaturated groups per molecule and thushas a functionality (f) of three. A dithiol is a polythiol with anaverage of two thiol groups per molecule and thus has a functionality(f) of two.

It is further understood and implied in the above definitions that inthese systems, the functionality of the polyene and the polythiolcomponent is commonly expressed in whole numbers although in practicethe actual functionality may be fractional. For example, a polyenecomponent having a nominal functionality of 2 (from theoreticalconsiderations alone) may in fact have an effective functionality ofsomewhat less than 2. In an attempted synthesis of a diene from a glycolin which the reaction proceeds to 100 percent of the theoretical valuefor complete reaction, the functionality (assuming 100 percent purestarting materials) would be 2.0. If, however, the reaction were carriedto only 95 percent of theory for complete reaction, about percent of themolecules present would have only one ene functional group, and theremay be a trace of material that would have no ene functional groups atall. Approximately 90 percent of the molecules, however, would have thedesired diene structure and the product as a whole then would have anactual functionality of 1.9. Such a product is useful in the instantinvention and is referred to herein as having a functionality of2.

The aforesaid polyenes and polythiols can, if desired, be formed orgenerated in situ and still fall within the scope of the instantinvention.

To obtain the maximum strength, solvent resistance, creep resistance,heat resistance and freedom from tackiness, the reaction componentsconsisting of the polyenes and polythiols of this invention areformulated in such a manner as to give solid, cross-linked threedimensional network polythioether polymer systems on curing. In order toachieve such infinite network formation, the individual polyenes andpolythiols must each have a functionality of at least 2 and the sum ofthe functionalities of the polyene and polythiol components must alwaysbe greater than 4. Blends and mixtures of the polyenes and thepolythiols containing said functionality are also operable herein.

In general, it is preferred, especially at or near the operable lowerlimits of functionality in the polyene and polythiol, to use thepolythiol and the polyene compounds in such amounts that there is onethiol group present for each ene group, it being understood that thetotal functionality of the system must be greater than four, and thefunctionality of the thiol and the diene must each be at least two. Forexample, if two moles of a triene are used, and a dithiol is used as thecuring agent, making the total functionality have a value of five, it ispreferable to use three moles of the dithiol. If much less than thisamount of the thiol is used, the curing rate will be lower and theproduct will be weaker in some respects because of the reducedcross-link density. If much more than the stoichiometric amount of thethiol is used, the rate of cure may be higher, if that is desirable,although excessive amounts can lead to a plasticized cross-linkedproduct which may not have the desired properties. However, it is withinthe scope of this invention to adjust the relative amounts of polyenesand polythiols to any values above the minimum scope disclosed hereinwhich give desirable properties to the cross-linked polythioether. Itmust be emphasized that regardless of the ratio of polythiol to polyene,the total functionality of the system must be greater than four, or across-linked network will not result, and the product will be aswellable, chain-extended composition which is unsuitable for thepurpose of this invention. Thus in practicing the instant invention toobtain a solid cross-linked photographic medium, it is necessary to usea polyene containing at least 2 unsaturated carbon to carbon bonds permolecule in an amount that the combined functionality of the unsaturatedcarbon to carbon bonds per molecule of polyene and the thiol groups permolecule of polythiol is greater than four.

The above systems are preferred. However, any system having an initialviscosity in the range 0-20 million centipoises at 130 C. which can befilled with pigment or dye and then either photopolymerized, photocuredor both to a solid polymer from which the unpolymerized material may bestripped by washing or other means is operable.

In the case of polyenes which are to be photopolymerized it ispreferable not to have a polythiol present in the composition, butrather to have only the ene monomer (usually a conjugated ene monomerwhich is commonly known as an addition polymerizable vinyl monomer) anda photoinitiator as the reactive components of the photopolymerizablecomposition. See U.S. Pat. Nos. 2,760,863; 3,380,831, etc., for examplesof some of these systems.

The liquid photosensitive compositions to be converted to solidphotographic material, in accord with the present invention may, ifdesired, include such additives as antioxidants, accelerators, dyes,inhibitors, activators, fillers, pigments, antistatic agents,flame-retardant agents, thickeners, thixotropic agents, surface-activeagents, light scattering agents, viscosity modifiers, extending oils,plasticizers, tackifiers and the like within the scope of thisinvention. Such additives are usually preblended with the monomer orcompound to be photosensitized or with the polyene or polythiol prior toor during the compounding step. Such fillers, however, unless they areused for the purpose of pigmenting or dying the image, should not besubstantially opaque when present in the photosensitizable polymer. Theaforesaid additives may be present in quantities up to 500 parts or moreper parts of the liquid photosensitive composition by weight andpreferably 0.005-300 parts on the same basis, but each additive must bepresent in an amount which will not interfere with or inhibit thenecessary photocuring or photopolymerization image-producing reaction orother required steps in the photographic process.

The colors of the continuous tone prints obtained by the practice of theinstant invention can be of infinite variety. For example, if onedesired a red and yellow print, a red pigment is included in thephotosensitive composition and the resultant photosensitized image islaminated to a piece of high reflectance yellow paper to give asilverless, red and yellow continuous tone photographic print. By thesame token, a yellow pigment can be employed and the photosensitizedimage can be laminated to a piece of high reflectance red paper.

For black and white prints, carbon blacks conventionally used for inks,plastics, rubbers, etc., may be employed as pigments. These include theso-called channel, furnace and thermal blacks having particle diametersof 5-250 millimicrons. Black dyes which are generally azine and azoorganic compounds are also operable. White TiO pigments are alsooperable.

For colored prints any suitably colored dye is operable that does notcontain groups which would inhibit the polymerization or curing systemused.

The support to which the photosensitive composition is adhered can beformed from various materials such as plastic, glass, guartz and thelike. The support is preferably a plastic having the characteristics ofbeing flexible, adherable to the photosensitive composition on exposureto UV radiation or by other means and can transmit a substantial amountof UV light. Operable plastic include but are not limited to,polyethylene, polypropylene, poly-4-methylpentene, polystyrene Mylar"i.e., polyethylene terephthalate, cellulose acetate and the like. Thethickness of the support is dependent on its relative strength anddimensional stability to hold a specified thickness of thephotosensitive composition and can be empirically determined by oneskilled in the art. Support films usually have a thickness of about 0.5to mils.

The photosensitive reaction can be initiated by actinic radiation fromsunlight or from special light sources which emit significant amounts ofactinic light suitably in the wavelength range of 2,200-4000 A underambient conditions or otherwise to obtain a solid elastomeric orresinous product useful as a photographic material after development.

The photosensitive reaction rate can be increased by the use of aphotosensitizer. As used herein a photosensitizer means either aphotoinitiator as employed in a polymerization reaction or a curing rateaccelerator as used in a curing reaction or both. For examplebenzophenone when added to a liquid photopolymerizable composition suchas monomeric pentaerythritol triacrylate would be a photoinitiatorwhereas benzophenone would be a curing rate accelerator for the liquidphotocurable composition comprised ofa polyene and a polythiol.

Various photosensitizers are operable and well known to those skilled inthe art. Examples of photosensitizers include, but are not limited to,benzophenone, acetophenone, acenapthene-quinone, methyl ethyl ketone,valerophenone, hexanophenone, a-phenylbutyrophenone, P-morpholinopropiophenone, dibenzosuberone, 4- morpholinobenzophenone,4'-morpholinodeoxybenzoin, pdiacetylbenzene, 4-aminobenzophenone,4-methoxyacetophenone, benzaldehyde, a-tetralone, 9- acetylphenanthrene,2-acetylphenanthrene, l0-thioxanthenone, 3-acetylphenanthrene,3-acetylindole, 9- fluorenone, l-indanone, 1,3,5-triacetylbenzene,thioxananthen-Q-one, xanthene -9-one, 7-H-benz[de]anthracen-7- one,l-naphthaldehyde, 4,4-bis (dimethylamino)benzophenone, fluorene-9-one,lacetonaphthone, 2'-acetonaphthone and 2,3-butanedione, etc., whichserve to give greatly reduced exposure times and thereby when used inconjunction with various forms of energetic radiation yield very rapid,commercially practical time cycles by the practice of the instantinventionv The photosensitizers, i.e., curing rate accelerators orphotoinitiators, are usually added in an amount ranging from 0.005 to 50percent by weight, suitably 0.0005 to 33 percent by weight, preferably0.5 to 25 percent, of the photocurable or photopolymerizable compositionin the instant invention. Such photosensitizers are also useful in thatthey control the contrast or gamma of the resulting image so that at lowconcentrations high contrast is obtained while at high concentrationslow contrast is obtained. Hence photographic printing materials can beprepared that are equivalent to the grades of silverbased printingpapers and can be matched to negatives of varying contrast.

The compounding of the components of the liquid photosensitivecomposition prior to exposure to UV radiation can be carried out inseveral ways. For example, in the case of the liquid photocurablecomposition, the polyene, the polythiol and any other additives, e.g.,photosensitizer, pigment or dye, are admixed in an inert atmosphere andcharged to an aerosol can, drum, tube, or cartridge for subsequent use.Exposure of said admixed components to actinic radiation throughimage-bearing transparencies under ambient or elevated temperatureconditions will initiate photocuring in the exposed areas.

Another useful method of compounding the photocurable composition is toprepare by conventional mixing techniques but in the absence of actinicradiation a composition consisting of polyene, antioxidant (to inhibitspontaneous oxygen-initiated curing), polythiol, pigment, UV sensitizeror photoinitiator, and other inert additives. This composition generallycan be stored in closed containers in the dark for extended periods oftime, but on exposure to actinic radiation (e.g., ultraviolet light,sunlight, etc.) through image-bearing transparencies will curecontrollably and in a very short time period in the exposed areas tosolid polythioether photographic products.

Conventional curing inhibitors or retarders operable with thephotocurable compositions in the instant invention include but are notlimited to hydroquinone; p-tert-butyl catechol;2,6-ditert-butyl-p-methylphenol; phenothiazine andN-phenyl-Z-napthylamine.

The molecular weight of the polyenes of the instant invention can bemeasured by various conventional methods including solution viscosity,osmotic pressure and gel permeation chromatography. Additionally, themolecular Weight can be sometimes calculated from the known molecularweight of the reactants.

The viscosity of the polyenes and polythiols was measured on aBrookfield Viscometer at temperatures up to C. in accord with theinstructions therefor.

The thickness of the photosensitive composition layer that is convertedto solid polymer is proportional to the intensity of the light thatstrikes it. Consequently, when exposed under a continuous tone negative,clear areas in the negative will correspond to thick areas of polymer,very dense areas in the negative to substantially no polymer andintermediate densities to intermediate thicknesses of polymer. Theinverse correspondence between the density of the negative and thethickness (and hence opacity) of the filled photosensitive polymerresults in the conversion of a continuous tone negative to a continuoustone print on both surfaces of the polymer layer. Likewise, if thematerial is used in a camera, a continuous tone scene will be renderedas a continuous tone negative on each surface of the polymer layer afterindependent exposure of each surface. Continuous tone separationnegatives will likewise yield continuous tone transparencies frompolymer films dyed with the complementary colors to the filters used toprepare the negatives. When these are superimposed, a continuous tone,full color print results.

The photosensitive material can be exposed to UV through a negative thatis in contact with a support layer or the negative image can beprojected onto a support layer or the material can be placed in a camerawith a support layer towards the lens and exposed like a conventionalphotographic film and thereafter be reexposed through the other supportlayer. The photosensitive polymer layer is sandwiched between twotransparent support layers of the same or various compositions e.g.,glass, quartz, plastic, etc., in which case the laminate can easily behandled in conventional photographic equipment such as cameras,enlargers, contact printing frames, etc.

The development of the exposed film is carried out by peeling thesupport layers apart and immersing each in an aqueous solutioncontaining a soap or detergent or a solvent, preferably alcohol.Depending on the development bath, i.e., whether water per se or soap ordetergent or solvent, etching periods ranging from 5 seconds up to 1hour or more optionally followed by blotting with a sponge or othermechemical means are employed, followed by drying with a current of airor by radiant heat. However, for some of the photosensitive compositionsthe resulting image contains minor imperfections even when etched forextended periods in conjunction with mechanical means. Thus it has beenfound that using an aqueous solution of detergent or soap or a solventin combination with ultrasonic activation of the bath to impartcavitation thereto, reduces etching time to periods of I second to 10minutes without enlisting mechanical aids such as brushes, sponges,etc., and the image obtained is far superior in quality and in fidelityof image reproduction to that previously obtained usingphotopolymerizable or photocurable materials and as good as thatobtained using silver films.

The difference in solubility between the cured areas in thephotosensitive layer and the portions of said layer which remain uncureddetermines the efficiency of the image making process. Also, the quickerthe exposed area becomes insoluble the more efficient the process. Thatis, the faster the cross-links in the photocurable composition areformed, the quicker a gel structure is developed with its resultinginsolubility in selective etching or wash-out solvents.

The solvent used for washing (i.e., developing the image) of thephotosensitized plate made from the photocurable compositions isprimarily a diluent which reduces the viscosity of the uncured mixtureso that it is easily removed. Removal can be speeded up, wherenecessary, by blotting with a sponge and the like. The washing liquid isselected so that it is readily miscible with or emulsified with theuncured material, yet has little action on the cured image or polymersupport. The preferred solvent liquids are water or water and adetergent and/or soap. Alcohols, such as ethanol, methanol or mixturesof methanol and/or ethanol, with methyl, ethyl or propyl acetate arealso operable for a large number of photocurable compositions. Othersolvents with high evaporation rates are well known to those skilled inthe art. It should be noted herein that the term solvent" includes notonly organic solvents but also water and other aqueous systems whereinthe unexposed photocurable layer is soluble (including dispersible insaid systems and the photocured portion is not so affected. The use ofaqueous systems as a solvent in the instant invention is advantageousnot only economically but also because of the elimination of the hazardsinvolved in handling organic solvents. In those instances where thephotocurable layer is acidic or basic the image can be developed bydissolving or dispersing the unexposed areas in an aqueous system of theopposite polarity, i.e., to use an aqueous acidic solvent system with abasic photocurable layer and vice versa. A specific'example of such asystem would be the use of an aqueous acidic developer such as a 20percent aqueous acetic acid solution with a photocurable layercomprising a polyene containing basic amino groups in its structure.Conversely, an aqueous alkaline developer, e.g., dilute aqueous sodiumhydroxide would be used with a photocurable layer containing acidicthiol groups. Obviously the degree of acidity or alkalinity should notbe allowed to reach those levels whereinthe essentially completelyphotocured areas are attacked. It is also possible in the instantinvention to wash at elevated temperatures wherein the solid uncuredportion of the photocurable composition melts and is removed as aliquid.

A convenient method of carrying out the process of this invention is toplace separate image bearing positive or negative continuous tonetransparencies in contact frames parallel to both surfaces of a layer ofa pigment or dye filled photosensilive composition, i.e., photocurableor photopolymerizable composition or both which has been sandwichedbetween transparent support layers and adjusted for uniformity of heightby suitable means, tag, a drawbar, precast mold and the like. The layerof the photosensitive composition is exposed through each transparencyand the transparent support layers to sources of actinic light suitablyin the wavelength range of 2,200-4,000 A, until the layer on both ofitssurfaces is cured or polymerized or both to an insoluble stage in theexposed areas.

To develop the images, the two support layers are pulled apart and eachis immersed in an appropriate water or solvent bath to remove theuncured or unpolymerized photosensitive composition from the unexposedareas. In some instances, development is speeded up by emergizing thedevelopment medium with ultrasonic energy, The photographictransparencies are thereafter dried in air or in an oven at elevatedtemperatures up to about 150 C. Furthermore, if desired, the thus formedimage can be further subjected to UV radiation for periods up 10 minutesto further harden it.

The resulting images on their transparent supports may be furtherprocessed in a number of ways:

1. If it is a negative made in a camera it may be used directly to makeprints by any conventional process.

2. If the transparency is a positive, it may be coated with anytransparent .adhesive or with a transparent photosensitive polymer laiddown upon any white reflecting material to give a black and white printand reexposed to UV radiation for adhesion. Ordinarilytransparentadhe'sives are also operable and do not require UVreexposure. Color prints of three or more separation positives can bemade in the same manner. Various tones may be obtained by varying thecolor cast of the support. Preferred backings are paper, vinyl and anyother black or white pigmented plastic.

3. If a transparency for projection is desired, the image can beprojected as is but preferably is laminated to another sheet of clear,transparent plastic to prevent possible handling damage to the imagematerial.

When practicing the instant invention, the amount of dye or pigment canbe added over fairly wide ranges. For example, 1 to 25 percent by weightof the photosensitive composition of a pigment can be added to obtaingood quality, continuous tone, photographic images. In the case of thedye, 0.1 to 25 percent by weight of the photosensitive composition of adye is employed to obtain continuous tone photographic images.

It is also possible to carry out the invention by exposing the sandwichcontaining the photosensitive composition to one source of UV lightthrough one of its support layers and a continuous tone image-bearingtransparency to obtain a latent image on one of the supports andthereafter turn the sandwich over and expose the other surface of thephotosensitive composition through the same or different continuous toneimagebearing transparency and obtain a latent image on the othersupport. The supports are then pulled apart as previously stated anddeveloped by immersing each in a bath which will remove the solubleunexposed photosensitive composition.

The following examples will aid in explaining, but should not be deemedas limiting, the instant invention. In all cases unless otherwise noted,all parts and percentages are by weight.

FORMATION OF POLYENE PREPOLYMER EXAMPLE 1 458 g. (0.23 moles) of acommercially available liquid polymeric diisocyanate sold under thetrade name Adiprene L-l00 by E. I duPont de Nemours & Co. was charged toa dry resin kettle maintained under a nitrogen atmosphere and equippedwith a condenser, stirrer, thermometer, and gas inlet and outlet. 37.8g. (0.65 moles) of allyl alcohol was charged to the kettle and thereaction was continued for 17 hours with stirring at C. Thereafter thenitrogen atmosphere was removed and the kettle was evacuated 8 hours at100 C. 50 cc. dry benzene was added to the kettle and the reactionproduct was azeotroped with benzene to remove the unreacted alcohol.This allyl terminated liquid prepolymer had a molecular weight ofapproximately 2,100 and will be referred to as Prepolymer A hereinafter.

EXAMPLE 2 400 g. (0.2 moles) of Adiprene L-lOO was charged to a dryresin kettle maintained under nitrogen and equipped with a condenser,stirrer, thermometer and gas inlet and outlet. 25.2 g. (0.43 moles)ofpropargyl alcohol (HC CCH OH) was added to the kettle and the reactionwas continued with stirring for 18 hours at C. Thereafter the nitrogenatmosphere was removed and the kettle was evacuated 16 hours at 100 C.followed by azeotropic distillations with 50 cc. water and then 50 cc.benzene to remove any excess propargyl alcohol. This H C-terminatedliquid prepolymer had a viscosity of 27,500 centipoises at 70 C. and amolecular weight of 2,100 and will be referred to as Prepolymer Bhereinafter.

EXAMPLE 3 1 mole of commercially available polyethylene glycol having amolecular weight of 1,450 and a specific gravity of 1.21 was charged toa resin kettle maintained under nitrogen and equipped with a condenser,stirrer, thermometer and a gas inlet and outlet. 2.9 g. dibutyl tindilaurate as a catalyst was charged to the kettle along with 2 molestolylene-2,4-diisocyanate and 2 mols of allyl alcohol. The reaction wascontinued with stirring at 60 C. for 2 hours. Thereafter a vacuum of 1mm. was applied for 2 hours at 60 C. to remove the excess alcohol. ThisCH C1-1 terminated prepolymer had a molecular weight of approximately1950 and will hereinafter be referred to as Prepolymer C.

EXAMPLE 4 1 mole ofa commercially available polyoxypropylene glycolhaving a molecular weight of about 1958 and a hydroxyl number of 57.6was charged to a resin kettle equipped with a condenser, stirrer,thermometer and a gas inlet and outlet. 4 g. of dibutyl tin dilaurate asa catalyst was added to the kettle along with 348 g. (2.0 moles) oftolylene-2,4-diisocyanate and 1 16 g. (2 moles) of allyl alcohol. Thereaction was carried out for minutes at room temperature under nitrogen.Excess alcohol was stripped from the reaction kettle by vacuum over a 1hour period. The thus formed Cl-l CH- terminated liquid prepolymer had amolecular weight of approximately 2,400 and will hereinafter be referredto as Prepolymer D.

EXAMPLE 5 750 g. of a N-containing tetrol (hydroxyl functionality 4)available from Wyandotte Chemicals Corp. under the trade name TetronicPolyol 904" having a M.W. of 7,500 was placed in a reaction vesselheated at 110 C. The flask was maintained under vacuum for 1 hour. Then,under an atmosphere of nitrogen, 0.1 cc. dibutyl tin dilaurate was addedand the flask was cooled to 50 C. Now 18.3 g. allyl isocyanate was addedslowly, maintaining the temperature at about 95 C. for about l hourafter the addition was completed. The thus formed polymeric polyene(i.e., Prepolymer E hereinafter) had a theoretical allyl functionalityof 2.2, a theoretical hydroxyl functionality of 1.8, and a calculatedmolecular weight of about 7,683.

EXAMPLE 6 To a resin kettle maintained under a nitrogen atmosphere andequipped with a condenser, stirrer, thermometer and gas inlet and outletwas added 843 g. of a commercially available liquid diisocyanateprepolymer sold under the trade name Multrathane 1 -196" by MobayChemical Co., said prepolymer having a molecular weight of about 1,680and an available isocyanate content of 4.7 5.2 percent. 87 g. (1.5moles) of allyl alcohol was added to the kettle and the reaction wascontinued for 18 hours at 140 C. with stirring. Thereafter the nitrogenatmosphere was removed and the kettle was evacuated for 22 hours at 100C. 50 cc. of dry benzene was added to the kettle and the reactionproduct was azetroped therewith to remove any unreacted alcohol. ThisCl'l CH- terminated liquid prepolymer had a viscosity of 25,000centipoises at 70 C. and a molecular weight of approximately l,800 andwill be referred to as Prepolymer F hereinafter.

EXAMPLE 7 678 g. (0.34 moles) of a commercially availablepolyoxypropylene glycol sold under the trade name NIAX by Union CarbideCo. and having a molecular weight of about 2,025 was degassed for 2hours at 100 C. and thereafter charged to a resin kettle maintainedunder a nitrogen atmosphere and equipped with a condenser, stirrer,thermometer and gas inlet and outlet. 118 g. (0.68 moles) of tolylene2,4-diisocyanate was charged to the kettle and the reaction was heatedwith stirring for 2% hours at 120 C. After cooling, 58 g. (1.0 moles) ofallyl alcohol was added to the kettle and the mixture was refluxed at120 C. for 16 hours under nitrogen. Excess allyl alcohol was removedovernight by vacuum at 100 C. Half of the allyl terminated liquidprepolymer having a viscosity of 19,400 cps. at 30 C. as measured on aBrookfield Viscometer was removed from the kettle. The other halfportion of the prepolymer was combined with 50 cc. of dry benzene andazeotroped overnight following which excess benzene was pulled out undervacuum for 5 hours at 120 C. This portion of the allyl-terminated liquidprepolymer had a viscosity of 1,560 cps. at 70 C. as measured on aBrookfield Viscometer and a molecular weight of approximately 2,500 andwill hereinafter be referred to as Prepolymer G.

EXAMPLE 8 751 g. (0.38 moles) of a commercially availablepolyoxypropylene glycol sold under the trade name Pluracol P 2010" byWyandotte Chemical Co. was degassed at room temperature for 3 hours andthen charged to a dry resin kettle maintained under a nitrogenatmosphere and equipped with a condenser, stirrer, thermometer and gasinlet and outlet. 132 g. (0.76 moles) of tolylene-2,4-diisocyanate wascharged to the kettle and the kettle was heated for 2 hours at 120 Cwith stirring under nitrogen. After cooling 58 g. 1.0 moles) of allylalcohol was added and the mixture was refluxed at 120 C. overnight.Excess allyl alcohol was stripped by vacuum overnight at 120 C. The thusformed allyl terminated liquid prepolymer had a viscosity of 1,500 cps.as measured on a Brookfield Viscometer at 70 C. and a molecular weightof approximately 2,500 and will hereinafter be referred to as PrepolymerH.

EXAMPLE 9 To a liter resin kettle equipped with stirrer, thermometer,gas inlet and outlet and heated to a temperature of 50 C. was charged610 g. (0.2 moles) of polytetramethylene ether glycol, commerciallyavailable from Quaker Oats Co. and having a hydroxyl number of 37.1along with 0.3 g. dibutyl tin dilaurate. The temperature of the kettlewas raised to C and the contents were freed of water under 1 millimetervacuum for 1 hour. The resin kettle was cooled to 60 C. and the systemwas placed under a protective atmosphere of nitrogen throughout theremainder of the reaction. 25.2 g. of allyl isocyanate, (0.4 mole) wasadded dropwise to the kettle at such a rate as to maintain thetemperature at 60 C. When the NCO content dropped to 0.54 mg./g., 1 mm.vacuum again was applied and the system was heated at 70 C. for onehour. The thus formed polymer product i.e., Prepolymer l, was a solid atroom temperature but at 50 C. is clear and pourable. The polymer producthad a viscosity of 1,800 centipoises at 70 C. as measured on aBrookfield Viscometer and an average molecular weight ofapproximately3,200.

EXAMPLE 10 To a 1 liter resin kettle equipped with stirrer, thermometer,gas inlet and outlet was charged 59] g. (0.30 moles) of apolyoxypropylene glycol commercially available from Union Carbide underthe trade name "PPG 2025 and 0.3 g. of dibutyl tin dilaurate. The kettlewas heated to 1 10 C. and the con tents were freed of water under 1 mm.vacuum for 1 hour. The kettle was cooled to 25 C. and the system wasplaced under a protective atmosphere of nitrogen throughout theremainder of the reaction. 53.1 ml. (49.8 g., 0.6 moles) of allylisocyanate commercially available from Chemetron Corp. was added to thesystem. An exotherm carried the temperature to 45 C. in 22 minutes.After 60 minutes, the NCO content (as determined by titration) was 0.04mg./g. The system was placed under 1 mm. vacuum and heated to 70 C. toremove traces of unreacted allyl isocyanate. The resultant polymerproduct had a viscosity of 600 centipoises at 30 C. as measured on aBrookfield Viscometer and an average molecular weight of approximately2,200 and will hereinafter be referred to as Prepolymer J.

The next two examples show a method of preparing the polyenes of theinstant invention by dehydration of polyether glycols.

EXAMPLE 11 100 g. of polypropylene glycol commercially available fromUnion Carbide under the trade name PPG 2025" was poured through a hottube filled with aluminum oxide at such a rate that the entire reactiontook place in 2 hours. The tube was 1 inch in diameter with the reactionzone l-ft. long and completely enclosed within a tube furnace. Thealumina catalyst was 10-18 mesh and was maintained at 350 C. using aLindberg Hevi-Duty tube furnace. The tube was fitted with a droppingfunnel and a nitrogen inlet at the top. Nitrogen pressure was kept onthe system throughout the reaction. The product collected from thebottom of the tube was analyzed for unsaturation by the mercuric acetatetitration method and was found to have 100 percent of the theoreticalamount of unsaturation expected after dehydration of both terminalhydroxyl groups of the polypropylene ether glycol. The polyene producthad a viscosity of 125 cps. at 70 C. and an average molecular weight ofapproximately 2,000 and will hereinafter be referred to as Prepolymer K.

EXAMPLE 12 1 kilogram of polypropylene ether glycol commerciallyavailable from Union Carbide under the trade name PPG 2025" was heatedto 120 C. in a round bottom flask. To this was added 120 ml. (20 percentexcess) of acetic anhydride at such a rate that the temperature of themixture was kept at 120-140 C. Following the addition, the mixture washeated at 140 C. for 4 hours. It was then cooled and diluted with anequal volume of chloroform, washed with percent aqueous sodiumcarbonate, then with water. The organic layer was separated and thechloroform was removed by distillation. Infrared analysis of thepurified material showed it to be the diacetate of the polypropyleneglycol with no residual hydroxyl groups.

100 g. of this diacetate was put through the hot tube as in Example 1 1except that the packing was glass helices instead of alumina and thetemperature was 375 C. The product contained 64 percent of thetheoretical amount of unsaturation expected after the elimination ofacetic acid from both terminal acetoxy groups of the polypropyleneglycol diacetate. The polymer will hereinafter be referred to asPrepolymer L.

EXAMPLE 13 114 g. of hexol sold under the trade name NIAX Polyol LS-490"by Union Carbide Chemicals Co. having a molecular weight of 684 wascharged to a 1 liter 4 neck flask and heated to 1 10 C. under vacuum andnitrogen for 1 hour. It was then cooled to approximately 60 C. where at0.1 cc. of dibutyl tin dilaurate was added followed by slowly adding 83g. (1 mole) of allyl isocyanate to keep the temperature in the range70-80 C. during the addition. After addition, the reaction was allowedto continue for 1 hour at 70 C. The polymeric hexaene product i.e.,Prepolymer M, had an average molecular weight of approximately 1,200 anda viscosity of 300 centipoises at 70 C.

EXAMPLE 14 To a 1 liter 4 neck flask was charged 300 milliliters ofdimethylformamide, 35 g. of tolylene-2,4-diisocyanate and 0.1 cc. ofdibutyl tin dilaurate. A mixture of 1 1.6 g. of allyl alcohol and 22.8g. of hexol commercially available from Union Carbide Chemical Co. underthe trade name NlAX Polyol LS490having a molecular weight of 684 wasslowly added to the flask. Temperature was kept at approximately 65 C.during the addition and for a period of 1 hour. The polymeric productobtained had an average molecular weight of approximately 2.100 and willbe referred to as Prepolymer N hereinafter.

EXAMPLE 15 To a 1 liter 4 neck flask was charged 100 cc. ofdimethylformamide, 100 g. of tolylene-2,4-diisocyanate and 0.1 cc.dibutyl tin dilaurate. 58 g. ofhexol, i.e., NlAX Polyol LS-490" by UnionCarbide and 34 g. of allyl alcohol were mixed together and addeddropwise to the flask. Before the addition to the flask was completed,the reaction, which was exothermic, gelled and the addition wasdiscontinued.

A comparison of Examples 13, 14 and 15 shows that Example 13 is animprovement over Examples 14 and 15 in that it allows one to formpolymer without the necessity of a solvent. A comparison of Examples 14and 15 shows that when starting with a highly functional polyol usingthe diisocyanate/allyl alcohol technique one must operate in dilutesolution to avoid premature cross-linking (i.e., gelation) which rendersthe polyene product useless as a curable liquid prepolymer. This problemis avoided completely by using the monoisocyanate technique illustratedin Example 13.

EXAMPLE 16 In a 1 liter, 4 neck flask 220 g. of hexol commerciallyavailable from Union Carbide Chemicals Co. under the trade name NlAXPolyol LS-490" (0.32 moles) and 0.1 cc. ofdibutyl tin i4; dilauratewasheated to 110 C. under vacuum for 1 hour. After cooling in nitrogento approximately 60 C g. of allyl isocyanate was added to the flask bymeans of a dropping funnel. The exothermic reaction produced atemperature of 100 C. When the addition was complete the reaction wascontinued at 70 C. for 1 hour. The resulting triene polymer product hadan average molecular weight of approximately 950 and a viscosity of 300centipoises as measured on a Brookfield Viscometer at 70 C. and will bereferred to as Prepolymer O hereinafter.

EXAMPLE 17 To a 1 liter 4 neck flask was charged 300 g. of a polyesterdiol (molecular weight 3,232) sold under the trade name RC Polyester S101-35 by R. C. Division, Hooker Chemical Corp. The flask was heated to110 C. under vacuum and maintained thereat for 1 hour. The flask wascooled to approximately 60 C., nitrogen was admitted, and 7.7 g. allylisocyanate and 8.1 g. of tolylene-2,4-diisocyanate was added by means ofa dropping funnel to the reaction at a moderate rate. A maximumtemperature of C. was needed. When the addition was complete, thereaction was allowed to continue at 70 C. for 1 hour. The thus formedsolid polymeric product had an average molecular weight of approximately6,800 and a viscosity of 13,600 centipoises when measured on aBrookfield Viscometer at 70 C. and will be referred to as Prepolymer Phereinafter.

EXAMPLE 18 To a 1 liter 4 neck flask heated at 110 C. was charged 808 g.of a polyester diol (having a molecular weight 3,232) sold under thetrade name RC Polyester S 101-35 by R.C. Division Hooker Chemical Corp.and 0.1 cc. dibutyl tin dilaurate. The flask was maintained under vacuumat 1 10 C. for 1 hour. The flask was cooled to approximately 50 C. andwith nitrogen passing through, a mixture of 10 g. of allyl alcohol and60 g. of tolyene-2,4-diisocyanate was added via a dropping funnel at amoderate rate. The reaction was allowed to continue for 15 minutes. Amaximum temperature of 90 C. was produced by the exothermic reaction.The polymeric product obtained was a solid at room temperature butliquid at 70 C. The product had an average molecular weight ofapproximately 10,500 and a viscosity of 270,000 centipoises at 70 C. andwill be referred to as Prepolymer Q hereinafter.

EXAMPLE 19 To a 2 liter flask equipped with stirrer, thermometer and gasinlet and outlet was charged 450 g. (0.45 moles) of polytetramethyleneether glycol, having a hydroxyl number of 112 and a molecular weight ofapproximately 1,000, along with 900 g. (0.45 moles) ofpolytetramethylene ether glycol having a hydroxyl number of 56 and amolecular weight of about 2000, both commercially available from QuakerOats Co. The flask was heated to 1 10 C. under vacuum and nitrogen andmaintained thereat for 1 hour. The flask was then cooled toapproximately 70 C. whereat 0.1 g. of dibutyl tin dilaurate was added tothe flask. A mixture of 78 g. (0.45 moles) of tolylene diisocyanate and78 g. (0.92 moles) of allyl isocyanate was thereafter added to the flaskdropwise with continuous stirring. The reaction was maintained at 70 C.for 1 hour after addition of all the reactants. The thus formed allylterminated polymer will hereinafter be referred to as Prepolymer R.

EXAMPLE 20 To a 2 liter flask equipped with stirrer, thermometer and gasinlet and outlet was charged 200 grams of a polyethyleneether glycolhaving a molecular weight of 400 (0.5 moles) and grams of apolyethyleneether glycol having a molecular weight of 4,000 (0.025moles). Stirring was commenced and the flask was heated to 60 C. Theflask was evacuated with a vacuum pump to remove any water present.After evacuation, two drops of dibutyl tin dilaurate (catalyst) wasadded and 100 ml. of allyl isocyanate was added by means of an additionfunnel over a 2-hour period. The reaction was continued at about 60 C.for 8 hours. The flask was then reevacuated by means of vacuum to removeexcess allyl isocyanate. The thus formed l allyl-terminated polymer,i.e., N,N'-diallyl urethane of EXAMPLE 42 poly(ethylene oxide) willhereinafter be referred to as g. of prepolymer S from Example 20, 4.5 g.of pen- Prepolymer taerythritol tetrakis (B-mercaptopropionate) and 1.5g. carbon black (Sterling ET) in ethylene glycol monoethylether EXAMPLE21 5 were mixed together and then heated in a vacuum oven for 5 minutesat 120 C. 1.0 g. of dibenzosuberone was then added and mixing wascontinued for 2 minutes. A 3 mil thick layer of this photosensitiveadmixture was spread on a sheet of cellulose acetate 5 mil thick andanother 5 mil thick sheet of cellulose acetate was rolled on top of thephotosensitive admixture to produce a sandwich. The sandwich of thephotosensitive material was cut to 5X4 inches and the edges sealed bybrief exposure to UV light. The film" so obtained was loaded intoGraphic cut film holders and inserted in a Polaroid MP 4 1 molediglycidyl ether of Bisphenol A having a molecular weight in the range370-384 and being commercially available from Shell Chemical Co. underthe trade name Epon 828 and 2 moles of diallylamine were stirred in abeaker at room 10 temperature (25 C.). The reaction was continued for 18hours during which time the exotherm and reaction temperature wasmaintained below 80 C. The resultant liquid polyene propolymer willhereinafter be referred to as Prepolymer T.

EXAMPLES 22 41 Technical camera fitted with a Goerz Dagor lens.Illumination of the subject (a watch lying on a three-color picture asTable 1 shows various photosensitive compositions which b k und) wassupplied by two 275 watt sunlamps. Expoare operable to obtain two imagessimultaneously on exposure sure as 10 t 15 in te at f 4,5. The film wasthen removed to UV light through an image-bearing transparency adjac nfrom the camera and turned over so that the other surface each supportlayer. The prepolymers from examples l-2l faced the lens. Under the sameconditions of illumination a were admixed with various polythiols,photosensitizers and a diff t bj t a htra lying on a three-color pictureas dye or pigment in the absence of UV light for periods rangingbackground) was photographed for 15 minutes at f 4.5. The from 2 minutesto 24 hours or more in order to obtain a film wa removed from thecamera, peeled apart and each homogenous mixture. A 2 mil layer of thesemixtures was 25 support layer was water-washed (60 C.) for a period of 5uniformly spread on a UV transparent support layer and minutes. Thesilverless photographic images obtained on each another UV transparentsupport layer was rolled on top of the support were laminated to awhite-pigmented polyvinyl photosensitive admixtures to produce asandwich. Each supchloride sheet with a commercial spray adhesive togive clear, port layer was 5 mils thick unless otherwise noted.silverless, black and white, continuous tone, photographic The thusformed sandwich was then exposed simultaneously prints of excellentquality. to 2 sources of actinic radiation. e.g., UV light, throughimage- It is obvious that the photographic film of the instantinvenbearing transparencies adjacent and in contact with each suptionwhich yields two images from a single layer of the port layer of thesandwich. Said exposure causes the photosenphotosensitive compositioncould readily be inserted in sitive layer to become insolubilized in theexposed areas on present day cameras with little or no adjustment to thecamera each surface of the photosensitive layer within periods rangingmechanism. That is, in a conventional camera after a roll of from about1 second to about 10 minutes. the film is finished on one side it couldbe turned over and The image was then developed in various solvents bypulling reused on the other side before development and processing.apart the two support layers and immersing each in an ap- Conventionalsilver halide film would need an intervening propriate solvent to removethe uncured soluble photosensilayer between each layer of silver halideto obtain two images tive mixture from the unexposed areas. Thedevelopment bath from the same frame on the film. was maintained attemperatures ranging from 20 to 65 C. The following example shows theuse of the instant inven- Thereafter each support layer with the imagethereon was tion to make a half tone negative from a continuous tonedried in air or in an oven at elevated temperatures up to aboutphotographic print. 150 C. The dry images were then laminated towhite-pig EXAMPLE 43 mented polyvinyl chloride sheets with a commercialspray ad- 45 Using the photosensitive composition of Example 42, thehesive "QUlK-STICK" or a UV curable adhesive to give a sil- Sandwlch W85P In a film holder behlnd a Kodak Contact I -1 black and white, screencontaining lines per inch. The film holder was TABLE I UV lightPolytliiol Photosensltizer Dye or pigment exposure Development Pre- Bup-Compari- Example polymer, port Tim 0, Time, tive rating No. type Type61115. Type Gms. Type Gms. layers Watts min. Bath min. of print 22 AQ-43 11.6 Benzopheiione.. 10 Carbon black... 15 X 275 2 Ethanol 3Excellent. 23... B Q-43 23.2 .-...d0 l0 do 15 X 275 2 .-...do 3 Fair.24... C Q-43 13.8 .....do 15 X 275 3 Water 5 Excellent. 25.-. D Q-4310.2 Acetophenone.-- 12 Y 275 4 lsopropanol--- 3 Good. 26... E Q-43 3.5...do 12 Y 4000 .20 .....do 5 Poor. 27... F 0,-43 10 Y 275 6 ..do 3Fair. 28... G Q,-43 7.5 X 275 5 .d0 3 Good. 29... H Q-43 9.8Benzoplierion 10 X 4000 25 Ethanol 3 Do.

I Q-43 7.6 Dibenzo- 7 5 X 4000 20 2 Excellent.

suberone. P-33 l2 1 7.5 Z 4000 2 Good. Q,43 12 2 10 Z 4000 3 Fair. Q-4320.0 10 4000 3 Poor. P-33 66.3 10 Z 4000 5 Fair. P-33 37.9 Dibenzo- 10 Z275 5 Do.

suberone. P33 7.5 Tltania 10 Z 4000 5 D0. 43 7.5 Carbon black... 10 Z4000 5 Do. Q-43 d 7.5 Z 4000 .40 .do 10 D0. Q-43 15 Z 4000 .20Isopropanol.-. 5 Excellent Q-43 40.0 ..-.do 7.5 Z 4000 .03 Water .5 D0.Q-43 55.0 Benz0phenone.. 7.5 .....do 7.5 X 4000 .03 Isopropanol..- 10Good. 1 All prepolymers are those identified by letter in examples 1-21.100 g. of Prepolymer was used in each of the examples in Table I. Q=43"Pentaerythritol tetrakis (fi-niercaptopropionaiae) and P-33".'Irlmethylolpropane trls (fi-mercaptopropionate). I Su\pp1ort layers areeither (X=polystyrene); (Y=polyethylene terephlhelate) or (Z=celluloseacetate) ;all films each 5 mils thick. U ght source either a 275 watttype RS sun lamp 9 inches away or a 4000 watt Ascorlux Xenon arc lamp1'.) inces away. Dye=Aquaprint 05-5207 Black K commercially availablefrom Interchemical Co. 6 Continuous tone positive transparencies usedwhen pigment is white 'IiOi. continuous tone, photographic print. (Acomparative rating of place in a 4 260K Camera n ning a f 16 lens- Thethe resultant print along with the data for the examples is camera wasfocused on a continuous tone, black and white shown in Table I.

film for an additional period of minutes. The film sandwich was removedfrom the film holder, stripped apart and washed with water at 60 C. fora period of 5 minutes, on each support layer.

The thus formed silverless photographic negatives were then usedsuccessfully to prepare the following articles:

a. a letterpress printing plate (20 mil image-relief) and a lithographicprinting plate (0.5 mils image-relief) according to the processdescribed in a copending application No. 674,773 filed Oct. 12, 1967 andincorporated herein by reference.

b. a photoengraving on metallic zinc using conventional photoresists andthe powderless etching technique (35 mils image-relief) as used byphotoengravers in the preparation of engravings for conversion toflexographic printing plates, and

c. a conventional silk-screen element which after exposure and wash-outwas useful for printing by the screen process printing method.

The following example shows a method of using the instant invention inmaking enlarged black and white prints.

EXAMPLE 44 A 35 mm. black and white negative was projected using ahome-slide projector, i.e., Kodak Carousel 750 manufactured by EastmanKodak Co. onto a sandwich of the photosensitive composition of Example42 so that the image was 8X10 inches in size. The projector was equippedwith a 500 watt DEK 120 volt 60 cycle lamp which yielded an intensity of380 microwatts/centimeter at the enlarged area. After an expo sure of 10minutes, the film was turned over and another 35 mm. black and whitenegative was projected on the other side of the photosensitivecomposition for a period of 10 minutes under the same conditions as setout heretofore. The film was then peeled apart and each support layerwas washed in warm water (60 C.) for a period of 5 minutes to developthe image. The resulting transparencies were laminated to whitepigmented polyvinyl chloride sheets to yield black and white prints. Itis to be understood that the negative to be enlarged by this process canbe a halftone, continuous tone, or line negative. Additionally, colornegatives or transparencies can be enlarged into black and white printsby the practice of this example.

The following examples represent a significant and notable departurefrom the ordinary concept of black and white photographic imagingmaterials and processes. This highly unusual situation arises becausethe photosensitive contrast-. forming medium supported on the film baseleads, on development, to a white-on-clear supported image rather thanthe customary black-on-clear supported image. This efiect (as noted inthe following examples) is accomplished by using a white-pigmentedphotocurable composition as the imageforming, contrast-formingphotosensitive medium.

The next result obtained by working with white-on-clear supported imagesis that these unusual photographic elements do not behave in aconventional manner. For example, a white-on-clear silverlessphotographic negative on contact printing with ordinary silver halidepaper will lead to a negative print rather than a positive. Similarly,if it is printed on the black-pigmented photocurable compositionprinting paper of this invention, the resulting print will be a negativeprint.

EXAMPLE 45 30 g. of Prepolymer R from Example 19, 2.72 ofpentaerythritol tetrakis (B-mercaptopropionate), 3.0 g. titanium dioxidepigment and 3.0 g. of dibenzosuberone were mixed together and thenheated in a vacuum oven for 2 minutes at 120 C. A 2 mil film of thismaterial was spread on a sheet of UV transparent cellulose acetate (5mil thick) and a 5 mil thick of UV transparent cellulose acetate wasrolled on top of but are the photosensitive material to produce asandwich. The sandwich was exposed under a continuous tone photographicnegative to ,a 4,000 watt pulsed xenon arc lamp 19 inches away for 5seconds. The sandwich was then turned over and reexposed to the samelamp for another 5 seconds. Thereafter the sandwich was peeled apart andthe uncured portion of the photosensitivecomposition was washed away inwarm water maintained at a temperature 60 C. The thus formed negativescan now be used repetitively to produce positives by the contact methodshown in this example by employing a black pigment or dye in thephotosensitive composition used herein in place of the TiO EXAMPLE 46Example 45 was repeated except that a positive transparency was usedinstead of the negative. The resultant images on the cellulose acetatesupports after washing were laminated to a glossy black background paperto give a direct positive continuous tone, black and white, photographicprint.

EXAMPLE 47 Example 46 was repeated except that a positive colortransparency was used instead of the positive black and whitetransparency. The resultant silverless, black and white continuous tonephotographic prints were of good quality.

v EXAMPLE 48 A 35 mm. positive color transparency was projected using ahome-slide projector, i.e., Kodak Carousel 750 manufactured by EastmanKodak Co. onto a sandwich of the photosensitive composition of Example45 so that the image was 8X10 inches in size. The projector was equippedwith a 500 watt DEK 120 volt 60 cycle lamp which yielded an intensity of380 microwatts/centimeter at the enlarged area. After an exposure of 10minutes on each side of the photosensitive composition, the sandwich waspeeled apart and the uncured photosensitive composition was washed awayfrom its support layer with warm water. The resulting transparencieswere laminated to glossy black filled polyvinyl chloride to give anenlarged silverless, continuous tone, black and white, photographicprint. It is to be understood that the transparency to be enlarged bythis process can be a halftone, continuous tone, or a line transparency.

The following example shows a method of forming direct prints in acamera from a white-pigmented photosensitive composition.

EXAMPLE 49 10 g. of Prepolymer S from Example 20, 2.72 g. ofpentaerythritol tetrakis (B-mercaptopropionate), 3.0 g. titanium dioxidepigment and 3.0 g. dibenzosuberone were mixed together and heated in avacuum oven for 5 minutes at 1 10 C. A 2 mil film of this material wasspread on a sheet of cellulose acetate (5 mil thick) and a 5 mil thicksheet of cellulose acetate was rolled on top of the photosensitivematerial to produce a sandwich of the photographic film. The sandwichwas put in a film holder and the holder was placed in a No. 4 Xeroxcamera containing a f 16 lens. The camera was focused on a continuoustone black and white print which was illuminated by four l,000 wattlamps. The film was exposed to UV light reflected from the continuoustone print for a period of 5 minutes and then the film was turned overand reexposed on its other side for an additional period of 5 minutes.The film sandwich was removed from the film holder, stripped apart anddeveloped by washing in water at 60 C. until the uncured portion of thephotosensitive composition was removed from each support. The thusformed positive images were laminated to black pigmented glossypolyvinyl chloride background material to give positive, silverless,black and white, continuous tone, photographic prints.

ln practicing the instant invention, it should be understood that allthe various combinations of polyenes and polythiols disclosed herein areoperable in all the various processes disclosed and claimed herein.Thus, in the photosensitive material used in all the various processes,operable polyenes include, not limited to, the reaction product ofpolytetramethylene etherglycol having a molecular weight of about 1,000,polytetramethylene ether glycol having a molecular weight of about2,000, tolylene diisocyanate and allyl isocyanate in a mole ratio of1:1:lz2 respectively; styrene/butadiene rubber; the reaction product ofpolytetramethylene ether glycol having a molecular weight in the rangeof about 650 to about 6,000 and allyl isocyanate in a mole ratio of 1:2respectively; the reaction product of a polyester diol and allylisocyanate in a mole ratio of 1:2 respectively; the reaction product ofpolyoxypropylene diol having a molecular weight in the range of about7004,000, tolylene 2,4-diisocyanate and allyl alcohol in a mole ratio of1:212 respectively; the reaction product of a phthalate or succinateesterol derived from polytetramethylene ether glycol and allylisocyanate having a molecular weight of about 4,000; the reactionproduct of polyethylene ether glycol having a molecular weight in the ofabout 600 to 6,000 and allyl isocyanate in a mole ratio of 1:2respectively; the reaction product of polyoxypropylene triol having amolecular weight in the range of about 3,000 to 6,000 and allylisocyanate in a mole ratio of 1:3 respectively, poly-1,3-butadiene; thetriacrylate of the reaction product of trimethylol propane and ethyleneoxide; triallyl urea; cellulose acetate methacrylate; the reactionproduct of 1,4-butanediol and allyl isocyanate in a mole ratio of 1:2respectively; the reaction product of poly (tetramethyleneether) glycol,tolylene diisocyanate and allyl alcohol in a mole ratio of 1:2:2respectively; and the polyene formed by reacting either (a) an organicepoxide containing at least two groups in its structure with a member ofthe group consisting of hydrazine, primary amines, secondary amines,tertiary amine salts, organic alcohols and organic acids wherein saidgroup members contain at least one organic substituent containing areactive ethylenically or ethynylically unsaturated group, or. (b) anorganic epoxide containing at least one organic substituent containing areactive ethylenically or ethynylically unsaturated group with a memberof the group consisting of hydrazine and an organic material containingat least two active hydrygen functions from the group consisting of Anyof the various polythiols encompassed by the definition herein areoperable with the aforesaid polyenes in any of the herein disclosed andclaimed processes to form the cured polythioether products of theinstant invention.

The composition used for forming the silverless photographic imagesofthe instant invention comprises 1. a liquid photosensitive materialhaving a viscosity in the range to 20 million centipoises at 130 C.,said material consisting essentially of(a) a polyene containing at leasttwo reactive unsaturated carbon to carbon bonds per molecule and (b) apolythiol containing at least two thiol groups per molecule, the totalcombined functionality of the reactive unsaturated carbon to carbonbonds per molecule in the polyene and the thiol groups per molecule inthe polythiol being greater than 4,

2. 0.0005 to 33 percent by weight of said composition of aphotosensitizer and 3. a member of the group consisting of l to 25% byweight of said composition ofa pigment and 0.1 to 25% by weight of saidcomposition of a dye, the weight ratio of the polyene to the polythiolbeing 298:982 respectively.

What is claimed is:

l. A process for forming two silverless continuous tone photographicimages from a single layer of photosensitive material which comprisesforming a photographic film by sandwiching a layer adjusted to a uniformthickness in the range 2 to 50 mils of a composition consistingessentially of a uniform mixture of( l a liquid photosensitive materialhaving a viscosity in the range 0 to 20 million centipoises at 130 C.consisting essentially of 98 to 2 percent by weight of said compositionofa polyene containing at least 2 reactive unsaturated carbon to carbonbonds per molecule and 2 to 98 percent by weight of said composition ofa polythiol containing at least 2 thiol groups per molecule, the totalcombined functionality of (a) the reactive unsaturated carbon to carbonbonds per molecule in the polyene and (b) the thiol groups per moleculein the polythiol being greater than 4; (2) 0.0005 to 33 percent byweight of said composition of a photosensitizer and (3) a member of thegroup consisting of l to 25 percent by weight of said composition of apigment and 0.1 to 25 percent by weight of a dye between two supportfilms both of which are transparent to actinic radiation, exposing saidcomposition on both its surfaces either simultaneously or concurrentlyto actinic radiation through an image-bearing, continuous tone,transparency maintained adjacent to said transparent support film,whereby portions of the composition exposed to actinic radiation on thetransparent support film proximate the actinic radiation source solidifyto form a reverse image relative to said image-bearing transparency,separating said imagebearing support films and removing soluble portionsof the composition in the unexposed areas thereby forming a silverless,continuous tone, photographic image on each support film.

2. The process according to claim 1 wherein said resultant photographicimage is laminated to a substantially non-transparent, contrastingbackground material to give a silverless continuous tone, photographicprint.

3. The process according to claim 2 wherein background material iswhite.

4. The process according to claim 1 wherein the support film is a memberof the group consisting of plastic, glass, and quartz.

5. The process according to claim 4 wherein the plastic is a member ofthe group consisting of polyethylene, polypropylene,poly-4-methylpentene, polystyrene, polyethylene terephthalate andcellulose acetate.

6. The process according to claim 1 wherein the composi tion contains inaddition a member of the group consisting ofa plasticizer, a filler, anodor mask, a light scattering agent and an antioxidant in an amountequal to 0.0005 to 500 parts per 100 parts of the composition.

7. The process according to claim 1 wherein the photosensitizer is amember of the group consisting of benzophenone, acetophenone,acenapthene-quinone, methyl ethyl ketone, valerophenone, hexanophenone,a-phenyl-butyrophenone, pmorpholinopropiophenone, dibenzosuberone, 4-morpholinobenzophenone, 4'-morpholinodeoxybenzoin, pdiacetylbenzene,4-aminobenzophenone, 4'methoxyacet ophenone, benzaldehyde, a-tetralone,9-acetylphenanthrene, 2-acetylphenanthrene, l-thioxanthenone, 3-acetylphenanthrene, 3-acetylindole, 9-fiuorenone, l-indanone, 1,3,S-triacetylbenzene, thioxanthen-9-one, xanthrene-9-one,7-H-benz[de]anthracene-7-one, l-naphthaldehyde, 4,4-bis (dimethylamino)benzophenone, fluorene-9- one, l-acetonaphthone, 2'-acetonaphthone,2,3-butanedione, tert.-butyl anthraquinone, benzoin, benzoin methylether, and mixtures thereof.

8. A process for forming two silverless, continuous tone, photographicimages from a single photosensitive layer in a camera which comprisesforming a photographic film by sandwiching a layer adjusted to a uniformthickness in the range 0.2 to 50 mils of a composition consistingessentially of a uniform mixture of l) a liquid photosensitive materialhaving a viscosity in the range 0 to 20 million centipoises at C.consisting essentially of 98 to 2 percent by weight of said compositionof a polyene containing at least 2 reactive unsaturated carbon to carbonbonds per molecule and 2 to 98 percent by weight of said composition ofa polythiol containing at least 2 thiol groups per molecule, the totalcombined functionality of the (a) the reactive unsaturated carbon tocarbon bonds per molecule in the polyene and (b) the thiol groups permolecule in the polythiol being greater than 4; (2) 0.0005 to 35 percentby weight of said composition of a photosensitizer and (3) a member ofthe group consisting of l to 25 percent by weight of said composition ofa pigment and 0.1 to 25 percent by weight of a dye, between two supportfilms both of which are transparent to actinic radiation, inserting thethus formed photographic film in a camera, exposing said photographicfilm to actinic radiation reflected from a continuous tone scene ontosaid composition thereby causing portions of the composition exposed toactinic radiation to form a solidified reverse image relative to saidscene on transparent support film proximate the aperture and/or lenssystem, turning the photographic film over and exposing the other sideof said composition to actinic radiation reflected from a continuoustone scene onto said composition thereby causing portions of thecomposition exposed to actinic radiation to form a solidified reverseimage relative to said scene on said other transparent support film,removing said photographic film sandwich from said camera, separatingsaid support films and removing the soluble unexposed portion of thephotosensitive composition from both support films thus forming asilverless, continuous tone, photographic image on each support film.

9. The process according to claim 8 wherein the resultant image islaminated to a substantially non-transparent, contrasting backgroundmaterial to give a continuous tone photographic print.

10. A process for forming two silverless half tone photographic imagesfrom a single photosensitive layer in a camera which comprises forming aphotographic film by sandwiching a layer adjusted to a uniform thicknessin the range 0.2 to 50 mils of a composition consisting essentially of auniform mixture of l) a liquid photosensitive material having aviscosity in the range to million centipoises at 130 C. consistingessentially of 98 to 2 percent by weight of said composition of apolyene containing at least 2 reactive unsaturated carbon to carbonbonds per molecule and 2 to 98 percent by weight of said composition ofa polythiol containing at least 2 thiol groups per molecule, the totalcombined functionality of (a) the reactive unsaturated carbon to carbonbonds per molecule in the polyene and (b) the thiol groups per moleculein the polythiol being greater than 4; (2) 0.0005 to 33% by weight ofsaid composition of a photosensitizer and (3) a member of the groupconsisting of 1 to percent by weight of said composition of a pigmentand 0.1 to 25 percent by weight of a dye, between two support films bothof which support films are transparent to actinic radiation, insertingthe thus formed photographic film in a camera, exposing saidphotographic film through a screen to actinic radiation reflected from acontinuous tone scene onto said composition thereby causing portions ofthe composition exposed to actinic radiation to form a solidifiedreverse image relative to said scene on said transparent support filmproximate the aperture and/0r lens system, turning the photographic filmover and exposing the other side of said composition through a screen toactinic radiation reflected from a continuous tone scene onto saidcomposition thereby causing portions of the composition exposed toactinic radiation to form a solidified reverse image relative to saidscene on said other transparent support film, removing said photographicfilm sandwich from said camera, separating said support films andremoving the soluble unexposed portion of the photosensitive compositionfrom both support films thus forming a silverless, half tone,photographic image on each support film.

11. The process according to claim 10 wherein the halftone image is useddirectly or is laminated to a transparent background material to give ahalf tone transparency.

12. The process according to claim 10 wherein the half tone image islaminated to a substantially non-transparent, contrasting, backgroundmaterial to give a half tone photographic rint.

p 13. A process for forming two enlarged, silverless, continuous tone,photographic images from a single layer of photosensitive material whichcomprises forming a photographic film by sandwiching a layer adjusted toa uniform thickness in the range 2 to 50 mils of a compositionconsisting essentially of a uniform mixture of (1) a liquidphotosensitive material having a viscosity in the range 0 to 20 millioncentipoises at C. consisting essentially of 98 to 2 percent by weight ofsaid composition of a polyene containing at least 2 reactive unsaturatedcarbon to carbon bonds per molecule and 2 to 98 percent by weight ofsaid composition of a polythiol containing at least 2 thiol groups permolecule, the total combined functionality of (a) the reactiveunsaturated carbon to carbon bonds per molecule in the polyene and (b)the thiol groups per molecule in the polythiol being greater than 4; (2)0.0005 to 33 percent by weight of said composition of a photosensitizerand (3) a member of the group consisting of 1 to 25 percent by weight ofsaid composition of a pigment and 0.1 to 25 percent by weight of saidcomposition ofa dye between two support films both support films beingtransparent to actinic radiation, projecting the actinic radiation in anenlarger apparatus through an image-bearing transparency mounted in theslide-holder provided, through the lens system onto one surface of saidcomposition for a time sufficient to solidify the portions of saidcomposition exposed to actinic radiation, in like matter exposing theother surface of said composition separating said support films andremoving the soluble unexposed portion of the photosensitive compositionfrom both support films thus forming an enlarge, silverless, continuoustone, photographic image on each support film.

14. The process according to claim 13 wherein the resultant enlargedimage is laminated to a substantially non-transparent, contrastingbackground material to give a continuous tone photographic print.

2. The process according to claim 1 wherein said resultant photographicimage is laminated to a substantially non-transparent, contrastingbackground material to give a silverless continuous tone, photographicprint.
 3. The process according to claim 2 wherein the backgroundmaterial is white.
 4. The process according to claim 1 wherein thesupport film is a member of the group consisting of plastic, glass, andquartz.
 5. The process according to claim 4 wherein the plastic is amember of the group consisting of polyethylene, polypropylene,poly-4-methylpentene, polystyrene, polyethylene terephthalate andcellulose acetate.
 6. The process according to claim 1 wherein thecomposition contains in addition a member of the group consisting of aplasticizer, a filler, an odor mask, a light scattering agent and anantioxidant in an amount equal to 0.0005 to 500 parts per 100 parts ofthe composition.
 7. The process according to claim 1 wherein thephotosensitizer is a member of the group consisting of benzophenone,acetophenone, acenapthene-quinone, methyl ethyl ketone, valerophenone,hexanophenone, Alpha -phenyl-butyrophenone, p-morpholinopropiophenone,dibenzosuberone, 4-morpholinobenzophenone, 4''-morpholinodeoxybenzoin,p-diacetylbenzene, 4-aminobenzophenone, 4''methoxyacetophenone,benzaldehyde, Alpha -tetralone, 9-acetylphenanthrene,2-acetylphenanthrene, 1-thioxanthenone, 3-acetylphenanthrene,3-acetylindole, 9-fluorenone, 1-indanone, 1,3,5-triacetylbenzene,thioxanthen-9-one, xanthrene-9-one, 7-H-benz(de)anthracene-7-one,1-naphthaldehyde, 4,4''-bis (dimethylamino) benzophenone,fluorene-9-one, 1''-acetonaphthone, 2''-acetonaphthone, 2,3-butanedione,tert.-butyl anthraquinone, benzoin, benzoin methyl ether, and mixturesthereof.
 8. A process for forming two silverless, continuous tone,photographic images from a single photosensitive layer in a camera whichcomprises forming a photographic film by sandwiching a layer adjusted toa uniform thickness in the range 0.2 to 50 mils of a compositionconsisting essentially of a uniform mixture of (1) a liquidphotosensitive material having a viscosity in the range 0 to 20 millioncentipoises at 130* C. consisting essentially of 98 to 2 percent byweight of said composition of a polyene containing at least 2 reactiveunsaturated carbon to carbon bonds per molecule and 2 to 98 percent byweight of said composition of a polythiol containing at least 2 thiolgroups per molecule, the total combined functionality of (a) thereactive unsaturated carbon to carbon bonds per molecule in the polyeneand (b) the thiol groups per molecule in the polythiol being greaterthan 4; (2) 0.0005 to 35 percent by weight of said composition of aphotosensitizer and (3) a member of the group consisting of 1 to 25percent by weight of said composition of a pigment and 0.1 to 25 percentby weight of a dye, between two support films both of which aretransparent to actinic radiation, inserting the thus formed photographicfilm in a camera, exposing said photographic film to actinic radiationreflected from a continuous tone scene onto said composition therebycausing portions of the composition exposed to actinic radiation to forma solidified reverse image relative to said scene on transparent supportfilm proximate the aperture and/or lens system, turning the photographicfilm over and exposing the other side of said composition to actinicradiation reflected from a continuous tone scene onto said compositionthereby causing portions of the composition exposed to actinic radiationto form a solidified reverse image relative to said scene on said othertransparent support film, removing said photographic film sandwich fromsaid camera, separating said support films and removing the solubleunexposed portion of the photosensitive composition from both supportfilms thus forming a silverless, continuous tone, photographic image oneach support film.
 9. The process according to claim 8 wherein theresultant image is laminated to a substantially non-transparent,contrasting background material to give a continuous tone photographicprint.
 10. A process for forming two silverless half tone photographicimages from a single photosensitive layer in a camera which comprisesforming a photographic film by sandwiching a layer adjusted to a uniformthickness in the range 0.2 to 50 mils of a composition consistingessentially of a uniform mixture of (1) a liquid photosensitive materialhaving a viscosity in the range 0 to 20 million centipoises at 130* C.consisting essentially of 98 to 2 percent by weight of said compositionof a polyene containing at least 2 reactive unsaturated carbon to carbonbonds per molecule and 2 to 98 percent by weight of said composition ofa polythiol containing at least 2 tHiol groups per molecule, the totalcombined functionality of (a) the reactive unsaturated carbon to carbonbonds per molecule in the polyene and (b) the thiol groups per moleculein the polythiol being greater than 4; (2) 0.0005 to 33% by weight ofsaid composition of a photosensitizer and (3) a member of the groupconsisting of 1 to 25 percent by weight of said composition of a pigmentand 0.1 to 25 percent by weight of a dye, between two support films bothof which support films are transparent to actinic radiation, insertingthe thus formed photographic film in a camera, exposing saidphotographic film through a screen to actinic radiation reflected from acontinuous tone scene onto said composition thereby causing portions ofthe composition exposed to actinic radiation to form a solidifiedreverse image relative to said scene on said transparent support filmproximate the aperture and/or lens system, turning the photographic filmover and exposing the other side of said composition through a screen toactinic radiation reflected from a continuous tone scene onto saidcomposition thereby causing portions of the composition exposed toactinic radiation to form a solidified reverse image relative to saidscene on said other transparent support film, removing said photographicfilm sandwich from said camera, separating said support films andremoving the soluble unexposed portion of the photosensitive compositionfrom both support films thus forming a silverless, half tone,photographic image on each support film.
 11. The process according toclaim 10 wherein the halftone image is used directly or is laminated toa transparent background material to give a half tone transparency. 12.The process according to claim 10 wherein the half tone image islaminated to a substantially non-transparent, contrasting, backgroundmaterial to give a half tone photographic print.
 13. A process forforming two enlarged, silverless, continuous tone, photographic imagesfrom a single layer of photosensitive material which comprises forming aphotographic film by sandwiching a layer adjusted to a uniform thicknessin the range 2 to 50 mils of a composition consisting essentially of auniform mixture of (1) a liquid photosensitive material having aviscosity in the range 0 to 20 million centipoises at 130* C. consistingessentially of 98 to 2 percent by weight of said composition of apolyene containing at least 2 reactive unsaturated carbon to carbonbonds per molecule and 2 to 98 percent by weight of said composition ofa polythiol containing at least 2 thiol groups per molecule, the totalcombined functionality of (a) the reactive unsaturated carbon to carbonbonds per molecule in the polyene and (b) the thiol groups per moleculein the polythiol being greater than 4; (2) 0.0005 to 33 percent byweight of said composition of a photosensitizer and (3) a member of thegroup consisting of 1 to 25 percent by weight of said composition of apigment and 0.1 to 25 percent by weight of said composition of a dyebetween two support films both support films being transparent toactinic radiation, projecting the actinic radiation in an enlargerapparatus through an image-bearing transparency mounted in theslide-holder provided, through the lens system onto one surface of saidcomposition for a time sufficient to solidify the portions of saidcomposition exposed to actinic radiation, in like matter exposing theother surface of said composition separating said support films andremoving the soluble unexposed portion of the photosensitive compositionfrom both support films thus forming an enlarge, silverless, continuoustone, photographic image on each support film.
 14. The process accordingto claim 13 wherein the resultant enlarged image is laminated to asubstantially non-transparent, contrasting backgrOund material to give acontinuous tone photographic print.